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More than 40 per cent of parents surveyed in the study admitted they used electronic devices to keep their children "calm and happy" for substantial periods.

Post-doctoral research fellow Pieter Coenen will present the preliminary results at the Inter-national Ergonomics Association congress in Melbourne next month.

He said the research hoped to uncover an appropriate level of device use for children younger than five.

"The behaviours they develop early in life can cause musculoskeletal issues later on in life," he said.

Guidelines in some countries advise a maximum one hour of screen time (including television) for children between two and five, with no electronic device use for children younger than two.

Yet the Curtin University study of 159 children aged five and younger, including 30 younger than two, found one-quarter watched TV for more than an hour a day during the week, rising to nearly half on weekends.

Sixty per cent spent up to an hour using tablets or mobile phones during the week, with nearly 10 per cent spending more than an hour a day on their tablets during the weekends.

Ms Cassidy said she limits her own daughter's use of her iPad, iPod and laptop while encouraging good posture and regular activity, mindful of research showing the dangers of prolonged sitting.

"If she is using them in bed or on the couch, I'm often saying: 'Use cushions to support yourself," she said.

"Everything points towards a maximum of 30 minutes (usage), then we should be moving again ... if kids start reporting symptoms of neck and back pain, these symptoms are often a sign that your body is not coping with what you're putting it through."

It comes after research by the charity Tablets for Schools found almost 70 per cent of primary and secondary schools in the UK now use tablet computers.

But the study also said there is no clear evidence of academic improvement for pupils using tablet devices.

A separate study from the National Literacy Trust found a quarter of secondary pupils described themselves as internet "addicts".

About two-thirds took a computer device or smartphone to bed with them, used for social media or watching videos.

Findings earlier last year from Ofcom showed about 70 per cent of five to 15-year-olds had access to a tablet at home.

Last month, clinical psychologist Linda Blair warned children should not be allowed to use phones and iPads before school because it can damage their concentration in class.